This invention relates to a method of making protein preparations from proteinaceous material. The protein preparations obtained are food functional and are intended to be used as food.
In recent years many methods have been developed for the production of protein concentrates intended for human consumption. However, most of these products have not been used for their intended purpose, but for animal food due to their lack of food functional properties. The ever increasing need for highly nutritional proteins calls for improved procedures which allow proteins from fish to be converted into food functional protein concentrates for use in conventional foods.
Many processes exist for the preparation of protein concentrates based on dissolving and recovery of the protein. Dissolution can be performed in water, organic solvents or mixtures thereof in order to separate the dissolved protein from insoluble matter.
Many proteins, particularly those in higher plants and microorganisms, are soluble in water alone or water containing some salt, while proteins in animal tissues are less soluble in water or weak salt solutions. Most proteins in most types of tissues are associated with other kinds of material such as carbohydrates and fat. Much of this non-protein material is associated with the protein when the latter is dissolved at high concentrations in water as in the case of the preparation of protein concentrates and thus the protein will still be contaminated with these carbohydrates and fat.
Protein preparations for food use should have functional properties involving a texture that can withstand chewing, high water and fat binding capacity, no contribution to flavor or still better a positive contribution to flavor, and a high nutritive value.
In order to facilitate the dissolution of large amounts of protein in water and to break its association with non protein material, various chemicals can be added. These chemicals are mostly alkaline, acid or hydrotropic agents as for example carbamide (urea) and guanidine hydrochloride.
For purposes of convenience and not limitation, the following discussions will refer to carbamide only as a hydrotropic agent. However, it is also intended that guanidine hydrochloride be equally applied as a hydrotropic agent.